1. Field of the Invention
Due to an ever growing shortage of conventional energy sources, there is an increasingly intense interest in harnessing solar energy. A limiting factor in the utilization of solar energy is the high cost of energy converters such as photovoltaic cells. Our invention provides a low cost means for achieving affordable solar energy by greatly reducing the cost of solar concentrators which increase (concentrate) the density of solar energy incident on the solar energy converter. For example, for the purpose of generating electricity, a large area of expensive solar cells may be replaced by a small area of high-grade photovoltaic solar cells operating in conjunction with the inexpensive intelligent mini-optics of our invention. Thus our invention can contribute to the goal of achieving environmentally clean energy on a large enough scale to be competitive with conventional energy sources.
Our invention is less expensive than conventional solar concentrators for two reasons. First due to miniaturization, the amount of material needed for the optical system is much less. Second, because our mini-optical solar concentrator is light-weight and flexible, it can easily be attached to existing structures. This is a great economic advantage over all existing solar concentrators which require the construction of a separate structure to support and orient them to intercept and properly reflect sunlight. Such separate structures must be able to survive gusts, windstorms, earthquakes, etc. The instant invention utilizes existing structures which are already capable of withstanding such inclement vicissitudes of nature.
2. Description of the Prior Art
There are many prior art patents that deal with twisting balls (gyricon) displays or separable balls displays. Electric or magnetic fields are used to orient or move these polarized or charged balls. To our knowledge none of the prior art utilizes the balls to optically concentrate (focus) light as in our invention. Furthermore the prior art neither teaches nor anticipates our application of the conversion of solar energy to electricity or any other form of energy. In one embodiment our invention incorporates balls with a shiny planar reflecting surface such as a metallic coating to give a high coefficient of reflectance. When the prior art refers to superior reflectance characteristics, they mean this in the context of displays with bi-colored balls e.g. black and white; or separable colored balls. In fact, the gyricon and separable ball prior art do not teach the focussing of light in any capacity. These verities are evident from an examination of the prior art. A large representative sample of the prior art will now be enumerated and described. This together with the references contained therein constitutes a comprehensive compendium of the prior art.
U.S. Pat. No. 5,754,332 issued to J. M. Crowley on May 19, 1998 deals with gyricon bi-colored balls whose reflectance is comparable with white paper. The object is to produce a monolayer gyricon display.
U.S. Pat. No. 5,808,783 issued to J. M. Crowley on Sep. 15, 1998 deals with gyricon bi-colored balls xe2x80x9chaving superior reflectance characteristics comparing favorably with those of white paper.xe2x80x9d Again the objective is a display application.
U.S. Pat. No. 5,914,805 issued to J. M. Crowley on Jun. 22, 1999 utilizes two sets of gyricon bi-colored balls xe2x80x9chaving superior reflectance charactreristics comparing favorably with those of white paperxe2x80x9d for display purposes.
U.S. Pat. No. 6,055,091 issued to N. K. Sheridon and J. M. Crowley on Apr. 25, 2000 utilizes gyricon bi-colored cylinders. Again the objective is a display application.
U.S. Pat. No. 6,072,621 issued to E. Kishi, T. Yagi and T. Ikeda on Jun. 6, 2000 utilizes sets of different mono-colored polarized balls which are separable for a display device.
U.S. Pat. No. 6,097,531 issued to N. K. Sheridon on Aug. 1, 2000 teaches a method for making magnetized elements (balls or cylinders) for a gyricon display.
U.S. Pat. No. 6,120.588 issued to J. M. Jacobson on Sep. 19, 2000 describes a display device which uses mono-colored elements that are electronically addressable to change the pattern of the display.
U.S. Pat. No. 6,174,153 issued to N. K. Sheridon on Jan. 16, 2001 teaches apparatus for this purpose for a gyricon display.
U.S. Pat. No. 6,192.890 B1 issued to D. H. Levy and J.-P. F. Cherry on Feb. 27, 2001 is for a changeable tattoo display using magnetic or electric fields to manipulate particles in the display.
U.S. Pat. No. 6,211,998 B1 issued to N. K. Sheridon on Apr. 3, 2001 teaches a method of addressing a display by a combination of magnetic and electric means. U.S. Pat. No. 6,262,707 B1 issued to N. K. Sheridon on Jul. 17, 2001 has a similar teaching for a gyricon display.
A large number of prior art devices have been described, all of which are directed at addressing and changing the pattern of a display device. While there are other such prior art teachings, none of them teaches or anticipates our invention.
xe2x80x9cBipolarxe2x80x9d refers herein to either a magnetic assemblage with the two poles north and south, or an electric system with + and xe2x88x92 charges separated as in an electret.
xe2x80x9cCollectorxe2x80x9d as used herein denotes any device for the conversion of solar energy into other forms such as electricity, heat, pressure, concentrated light, etc.
xe2x80x9cCompactionxe2x80x9d refers to increasing the density of a collection (ensemble) of objects by geometrical arrangement or other means.
xe2x80x9cElastomerxe2x80x9d is a material such as synthetic rubber or plastic, which at ordinary temperatures can be stretched substantially under low stress, and upon immediate release of the stress, will return with force to approximately its original length.
xe2x80x9cElectretxe2x80x9d refers to a solid dielectric possessing persistent electric polarization, by virtue of a long time constant for decay of charge separation.
xe2x80x9cElectrophoresis or Electrophoreticxe2x80x9d is an electrochemical process in which colloidal particles or macromolecules with a net electric charge migrate in a solution under the influence of an electric current. It is also known as cataphoresis.
xe2x80x9cFocussing planar mirrorxe2x80x9d is a thin almost planar mirror constructed with stepped varying angles so as to have the optical properties of a much thicker concave (or convex) mirror. It can heuristically be thought of somewhat as the projection of thin equi-angular segments of small portions of a thick mirror upon a planar surface. It is a focusing planar reflecting surface much like a planar Fresnel lens is a focusing transmitting surface. The tracking-focussing property of an ensemble of tiny elements which make up the focussing planar mirror are an essential feature of the instant invention.
xe2x80x9cHeliostatxe2x80x9d denotes a clock-driven mounting for automatically and continuously pointing apparatus in the direction of the sun.
xe2x80x9cImmisciblexe2x80x9d herein refers to two fluids which are incapable of mixing.
xe2x80x9cPacking fractionxe2x80x9d herein refers to the fraction of an available volume or area occupied by a collection (ensemble) of objects.
xe2x80x9cPolar gradientxe2x80x9d as used herein relates to magnetic optical elements that are controlled in the non-gyricon mode such as in the magnetic field gradient mode.
xe2x80x9cMonopolarxe2x80x9d as used herein denotes mono-charged optical elements that are controlled in the non-gyricon mode such as the electrophoretic mode.
xe2x80x9cRayleigh limitxe2x80x9d relates to the optical limit of resolution which can be used to determine the smallest size of the elements that constitute a mini-mirror. Lord Rayleigh discovered this limit from a study of the appearance of the diffraction patterns of closely spaced point sources.
xe2x80x9cSpin glassxe2x80x9d refers to a wide variety of materials which contain interacting atomic magnetic moments. They possess a form of disorder, in which the magnetic susceptability undergoes an abrupt change at what is called the freezing temperature for the spin system.
xe2x80x9cThermoplasticxe2x80x9d refers to materials with a molecular structure that will soften when heated and harden when cooled. This includes materials such as vinyls, nylons, elastomers, fuorocarbons, polyethylenes, styrene, acrylics, cellulosics, etc.
xe2x80x9cTranslucentxe2x80x9d as used herein refers to materials that pass light of only certain wavelengths so that the transmitted light is colored.
There are many aspects and applications of this invention. Primarily this invention deals with the broad general concept of method and apparatus for focussing light. A particularly important application is the focussing of sunlight for power conversion and production.
It is a general object of this invention to provide a focussing planar mini-optic system for reflecting light with a substantially higher power density than the incident light.
One object is to provide an inexpensive, light-weight, and flexible mini-optical light concentrator that can easily be attached to existing structures, and thus does not require the construction of a superstructure of its own.
Another objective is to provide a solar energy conversion system that is not only low capital cost, but that is also inexpensive to install.
A particularly important object is to provide a unique tracking and focussing system for solar power conversion.
Another object is to provide a system that holds or locks the mini-mirror elements in rigid orientation with minimal to no-power expenditure between rotational focussing operations.
Another object is to provide a means for unlocking the mini-mirror elements so that they may rotate freely when being guided into the proper orientation.
Another object is to provide an inexpensive system for photovoltaic conversion.
Another objective is to provide daily peaking power when the load is highest on the conventional power grid.
Another objective is to provide electricity to remote villages or rural settlements.
Another object is to provide a rugged system for conversion of solar energy to heat.
Another objective is to provide electricity for communications installations.
Another object is to provide large-scale environmentally clean energy.
Another objective is to help in the industrialization of developing countries.
Another object is to provide a low-cost, tough, light-weight, concentrated efficient solare energy converter that is highly portable.
Another objective is to provide a minitiarized planar heliostat field configuration that can either track the sun temporally, or follow the sun with a photomultiplier which searches for a maximum output.
Another object is to provide a portable system that can easily go anywhere man can go, to track and concentrate the sun""s energy.
Other objects and advantages of the invention will be apparent in a description of specific embodiments thereof, given by way of example only, to enable one skilled in the art to readily practice the invention as described hereinafter with reference to the accompanying drawings.
In accordance with the illustrated preferred embodiments, method and apparatus are presented that are capable of producing and maintaining a high concentration of light relative to the original source such as sunlight. The embodiments are all capable of secure attachment to sturdy existing structures to provide an inexpensive application with a long and trouble-free life.